Metal tube



Jan. 19, 1 932. G. E. NEUBERTH METAL TUBE Filed April 11, 1931 2 Sheets-Sheet l 6 INVENTL r; BYZJ. ATTORNEYS 2 Sheets-Sheet 2 Jan. 19, 1932. G. E. NEUBERTH METAL TUBE Filed April 11, 1931 V INVENTOR d". W

' ATT0RNEY I ill Patented Jan. 19, 1932 UNITED "STATES,

GEORGE E. NE' UBEB'IH, 0] NEWARK, NEW JERSEY, ASSIGNOB, BY KESNE LSSIGN- MENTS, TO TUBE REDUCING CORPORATION, OF WILIIN'GTON,- DELAWARE, A

CORPORATION 01 DELAWARE urn. TUBE Application in Apr-i111,

When a metallic tube is subjected to tensional stresses in a cold working process so as to elongate it and reduce its cross-sectional area, e. g. in cold drawing, the 1nd1v1dual grains or crystals of the metal, when examined microscopically, exhibit what are commonly known as slip-lines extending cross-wise of the grain at a substantlal angle (30 degrees or more) to the dlrectionof elongation. There may be one or more sets of these slip-lines in each grain, the lines in each set being substantially parallel; and, as a rule, these lines increase and become more apparent with the degree of work ng as the latter approaches the limiting point where further working causes a rupture of the tube. (See, for example, Figures 15 and 16 n Technical Publication No. 93 of the American Institute of Mining and Metallurgical Engineers, by Frank W. Harris, 1928.) These slip-lines are generally understood to ind1- cate a slippage of the component parts or blocks of each crystal with respect to one another; and are exhibited when, upon the application of mechanical stresses, the individual crystals are subdivided into smaller blocks or fragments which tend to slide upon each other. If these stresses are continued indefinitely, there is complete separation and the crystals are broken along these lines. If

in cold drawing, for example, the working ofv the metal is continued too far, annealing will not consolidate or reorganize the crystals, and rupture of the metal soon follows. In cold drawing, therefore, annealing is resorted to before rupture of the metal occurs in order that the crystals may be consolidated, i. e. returned to their normal condition, in

which case the'slip-lines disappear. Thus, cold drawing as practiced heretofore, has consisted of alternate drawing and annealing operations which were continued until the ultimate reduction or elongation desired had been reached.

In my copending patent application Serial No. 229,887, filed October v31, 1927, Patent No. 1,810,855, dated June 16, 1931, I have illustrated and described a method of cold working metallic tubes, in accordance with which their elongation and reduction may 1931. Serial ll'o. 528,584. v

be carried to an almost unlimited extent without annealing and with no tendency of the metal to rupture. It results, therefore, that my method of reduction or elongation enables one to reduce, if not dispense entirely with, the alternate annealings.

When I filed my copending patent application" aforesaid, I realized that, in accordance with my method, the action of the forces set up within the metal of the tube produced a diflerent result in the metallic structure thereof from any produced by methods of cold working now in common use, and that it was due to this structural difference that the elongation or reduction could be continued indefinitely without rupturing the metal; and in referring to this diiference I then stated it as follows: The (my) method also works the metal of the tube so that it is given a grain or, rather, it has elongated longitudinal fibre established.

When specimens of tubesproduced by my process are properly etched to disclose intracrystalline detail and are examined under the microscope or by photomicro raphs, (longitudinal sections being taken t rough the axis of the tube) visible slip-lines which are characteristic of ordinary cold worked metals are lacking in a majority of the grains, if not entirely absent, and instead, lines (which for convenience may hereinafter be called fold lines and which for the most part are wholly disassociatedfrom the sliplines) appear, extending substantially arallel to the axis of elongation, which sai lines indicate alternate ridges and valleys in the surface of the etched metal. These ridges and valleys give the appearance, under the microscope and in photomicrographs, of elongated longitudinal fibers.

It is believed-that these fold lines may indicate an intracrystalline fragmentation in which the fragments, instead of being dis posed in planes extending at an angle to the axis of elongation as in ordinary cold work, are disposed in planes extending substantially parallel to the axis of elon ation. Another interpretation of these fol lines is that they may represent fluid move ment of molecules within the crystals. In any event, res gardless of the inter retation, it is found that on tubes disclosing the characteristic fold lines described above, and failing to disclose the ordinary slip-lines in a majority of the grains, cold working may be continued 'almost indefinitel without annealing. Thus,

taking for examp e mild steel tube and workin by known drawing methods, whereas it is possible to make a one and one-half to one reduction without annealing, it is not feasible in ordinary commercial operations to make greater reductions without annealing. The tube formed as a result of this drawin would be hi hly embrittled.

On t e other han by applying a preponderance of compressive stresses in such manner as to produce a tube disclosing the above described fold lines rather than slip lines it has been found possible, starting with the same mild steel tube, to make a seventeen to one reduction without annealing, and in certain cases even greater reductions may be effected without destroying the characteristics of the metal, When these relatively high reductions are made the crystals a pear to be met ed so that no distinct boun aries between t e crystals can be developed by etching, and the entire surface of the sections shows fold lines.

With other metal tubes which can be reduced by cold drawin and cold rolling methods, it has also been 0 served that where such tubes are worked by compressive stress methods to produce the above described effect, many times as much working can be done without annealing and without destroying the characteristics of the metal.

Tubes of certain metals, as for example, Monel metal and certain special steels have not heretofore been successfully reduced by cold drawing methods except at great expense due to the low reductions possible and the necessity of frequent annealing. When worked by m method to produce fold lines rather than s ip lines, it has been found possible to reduce such tubes, and to make without difliculty reductions as great as three to one. Greater reductions can be and have been made in certain cases.

It will be understood that tubes'worked by known drawing and rolling processes may disclose to microsco ic examination, occasional grains distri uted here and there throughout the metal in which no slip-lines appear or in which the slip-lines produced by cold work lie in planes parallel to the axis of elongation. Conversely, tubes worked by my method may disclose coca-- sional grains in which no fold lines appear or in which slip-lines appear which are disposed in lanes lying 'atan angle to the axis of e ongation." In mild steel tubes worked by my process, for example,;-;ordinary s li -lines do not appear in more than onehr of the grains. This may result from the fact that occasional ains are so sha d or oriented that wor 'ng by any met 0d causes a result departing from the normal, as represented by the majority of the grains. It has been noted, however, that as working proceeds, the tendency to conform to the normal intracrystalline efiect of the working is increased, so that the greater the degree of working, the fewer are these observable departures from the normal.

Since one method and apparatusfor produsing metal tubes having the above described intracrystalline structure is described in my copending application aforesaid, and since I referred to it therein as having an elongated longitudinal fiber, the present aplication is to be regarded as a continuation 1n part of the aforesaid application. An improved method and apparatus for producing tubes having the above described intracrystalline structure is also described in my copending application Serial No. 353,717, filed April 9, 1929, Patent No. 1,810,886, dated June 16, 1931, but it will be understood that the said tubes may be produced by other methods, and the invention herein claimed is in no sense limited to tubes so produced.

In the drawings, Figure 1 shows the above described fold lines in the initial stages of their development, this figure bein a reproduction of a photomicrograph ta en at a magnification of one thousand diameters, of a tube which has been submitted to a two and 1 one-half to one reduction. The initial development of the longitudinal fold lines giving the appearance of an intracrystalline longitudinal fiber is lainl apparent in the crystal extending a on t e middle of Figure 1 as indicated by re erence character a. Figure 2 is a similar reproduction of a photomicrograph taken at a magnification of one thousand diameters, of metal which has been submitted to a reduction of six and one-half to one. The development of the fold lines I) is considerably more marked and the appearance of longitudinal fibres is quite distinct.

Figure 3 is a similar reproduction of a photomicrograph taken at a magnification of one thousandiameters of metal which has been submitted to a'reduction of thirteen to one. In thistfigure the development of the fold lines 0 and the ap arance of longitudinal fibres is increasing y apparent.

In each of the above figures the absence of ordinary transverse slip-lines will be apparent.

Figure 4-is a similar reproduction of a photomicrogra h taken at a magnification of one thousand diameters of metal worked by an especially effective cold drawing process,

and submitted to a reduction of two and one- Y closures of my aforesaid copcnding applications may be referred to for a more complete disclosure.

Figures 5a and 5?) represent the sta e in the preferred cycle of operation at whic 1 the reducing devices 1 have reached their rearmost position relative to the stock 2 andthe latter has just been fed forward relative to the longitudinally fixed tapered mandrel 3.

The stock, as shown in Figure 5b, is round and slightly loose on the mandrel from the preceding consolidating action. I The. arrows indicate that the next movement which will occur will be a'forward action of the reducin devices.

'igures 6a and 6?) represent the stage in the cycle at which the reducin devices have moved forward to the end 0 the reducing stroke. The stock, as shown in Figure 6b, is slightly elliptical and ribs or incipient fins 4 show on the side of the tube where the roll grooves met. The arrow indicates that the next movement will be a turning of the tube and mandrel.

Figures 7a and 76 re resent the stage in the cycle at which the tu and mandrel have been turned 90 and the reducing devices are ready to commence their rearward movement as indicated by the arrows.

Figures 8a and 86 represent the 'stage in the cycle at which the reducing devices have com leted their rearward movement or consoli ating action. The arrows indicate that the next movement will be the forward feeding of the tube along the mandrel.

It will be understood that the invention may be variously modified and embodied within the scope of the subjoined claims.

I claim as my invention:

1. As an article of manufacture a metal tube characterized by this: that the surfaces of a majority of the crystals in a longitudinal section taken through the longitudinal axis thereof appear to be made up for the most part of elongated longitudinal fibres.

2. As an article of manufacture a metal tube characterized by this: that in a longitudinal section taken through the longitudinal axis thereof a majority of the crystals appear elongated with surfaces made up for the most part of elongated longitudinal fibres.

3. As an article of manufacture a metal tube characterized by this: that in a section taken through the longitudinal axis thereof the surfaces of the majority of the crystals appear to be made up of elongated longitudinal fibres and to be free of slip-lines.

4:. As an article of manufacture a metal tube characterized In this :that in a longitudinal section taken tirough the longitudinal axis thereof the surfaces of the majority of the crystals appear to be made up of clongated longitudinal fibres and the surfaces of not more than one-third of the crystals appear to have slip-lines.

5. As an. article of manufacture a metaltube characterized by this: that in a longitudinal section taken through thelongitudinal axis thereof the surfaces of the ma ority of the crystals exhibit at least one fold line and are substantially free from slip-lines.

6. As an article of manufacture a metal tube characterized by this: that in a longitudinal section taken through the longitudinal axis thereof the surfaces of the majority of the crystals exhibit a plurality of fold lines and are substantially .free from sliplines.

7. As an article of manufacture a metal tube characterized by this: that in a longitudinal section taken through the longitudinal axis thereof the crystals appear to be merged and the entire surface of t e section to consist of longitudinal fold lines.

8. As an article of manufacture a metal tube characterized by this: that in a longitudinal section taken parallel to the longitudinal axis thereof the surfaces of the majority of the crystals appear to be made up of elongated longitudinal fibres and the surfaces of less than one-third of the crystals appear to have slip-lines forming an angle greater than thirty degrees with said axis.

9. As an article of manufacture a metal tube characterized by this: that in a lo.n i-

tudinal section taken parallel to the longitu inal axis thereof the crystals are elongated and the surfaces of a majority of the crystals exhibit no slip-lines.

10. As an article of manufacture a metal tube characterized by this: that in a longitudinal section taken parallel to the longitudinal axis thereof the crystals are elongated and the surfaces of a majority of the crystals exhibit substantially no angular lines other than fold-lines.

11. As an article of manufacture a metal tube characterized by this: that in a longitudinal section taken-parallel to the longitudinal axis thereof the surfaces of two-thirds of the crystals exhibit substantially no angular lines other than fold-lines.-

12. As an article of manufacture, a metal tube in which the intracrystalline structure is characterized by the presence, in a majority of the crystals, of fold lines extending substantially parallel to the axis of elongation of the tube, and by the substantial absence of slip-lines.

13. As an article of manufacture, a metal tubein which the intracrystalline structure is characterized by the presence, in a majorill 10 substantially i,sas,sso

ity of the crystals, of fold lines extending substantially parallel to the axis of elongation of the tube and b the absence, from a majority of the crysta s, of slip-lines extending at an angle .to the said axis of elongation.

14. As an article of manufacture, a metal tube in which the intracrystalline structure, in a majority of the crystals, comprises for the most part fragments disposed in lanes arallel to the axis of e ongation of the tu e.

In testimony whereof, I have signed my name to this specification this 10th day of April, 1931. t

GEORGE E. NEUBERTH.

cmmcmor comc'non.

Patcat Ne. 1,842.28 0.

GEORGE E. NEUBERTH.

' It is hereby certified that errorappears inthe printed specification of the above nmbered patent requiring correction as follows: Page 1, line 47, for the number "1,810,855" read 1,810,885: and that the said Letters Patent should he read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 22nd day of March, A. D. 1932.

bLLbloore,

(Seal) Acting Comisaioaer of Patent!- Granted January 19, 1932, to 

